This one will get me flamed but I’m just throwing it out there, Have been surfing the forum for a few months now and I have to say that it's pretty much become my daily routine like Facebook and shit. But I am trying to piece together some parts here and there while learning and making new friends at the same time.

Getting to the point….
There should be a standard when selling purchased goods, used or not. I understand that there are certain things like the 1M that can command their own price, but I mean small things like wheels and other mods should have a standard 20% reduction then depreciate by condition.

E.G. Cobb AP
Retail $895 -20% = Resale Price $716 Shipped – Which is the FMV for this particular item clean and in good working order
The average is $700, which is on par with my concept here.

Now let’s take an Avant Garde M359 19” With a little rash on 1 wheel, no tires
Retail $1099-20%=$879 – Condition thereafter, which should equal the cost of repair, let’s say $100 per wheel for sake of argument using whatever process that you believe in. This brings the AG M359 wheels to $779 which is a fair price for the resold wheels in like new condition.

Now this model can be applied to price lots of items and is also a way everyone can win. This concept is not new, it is also how you get the car values. KBB uses a similar pricing model but with real market data and more complex algorithms of course but it does keep the seller and buyer in an agreement when determining value and depreciation.

Of course this does not apply to shipping, rare goods, or in any way have to with bargaining but just my .02 to keep the trade moving.

True. But in the case of the wheels, the shop that the seller may use to repair the wheel may only charge $50, where as the shop that the buyer may use may charge $100. Which means the seller thinks that the wheels are valued at $50 more than the buyer.
I agree with what you're saying. The best advice I can give is to shop around, know what the going price for certain things are, and don't be afraid to haggle. In some cases sme people just want it out of their garage.